Self-diffusion coefficient of hydrogen in NbH06

Direct measurements of the self-diffusion coefficient D of hydrogen in a hydrided single crystal of niobium were made between 90 and 2430C using the NMR pulsed-field-gradient technique. For Nb0.6 in the α' phase, D = D0 exp (-E/sub alpha//kT), where D0 = 6.6 x 10-4 cm2/sec and E/sub alpha/ = 0.165 +- 0.008 eV/atom. By combining measurements of D and the spin-lattice relaxation rate for hydrogen, it is found that the rms jump distance [l2]/sup 1/2/ has a value within the range 0.5b less than or equal to [l2]/sup 1/2/ less than or equal to 0.8b, where b is the bcc lattice constant. Measurements of D are compared with published results for other hydrogen concentrations as obtained from quasielastic neutron scattering and Gorsky-effect experiments